Maximum Force Capacity of Back Extensor Muscles in Healthy Women and Men: Not Different, If Anthropometrically Normalized

In the present study, data were compiled to compare trunk extension strength between healthy female and male participants. Participants (124 females, 115 males) performed isometric maximal voluntary contraction (MVC) tests in an upright standing position. In addition, upper body weight was determined. Outcome parameters included maximal force values, expressed as torque, as well as upper body weight (also in torque values). Furthermore, the ratio between MVC and upper body weight was calculated. Highly significant differences were observed for MVC (men: 241 Nm, women: 162 Nm, p< 0.0001) and for upper body torque (men: 115 Nm, women: 80 Nm, p< 0.0001). After normalization to upper body torque, no relevant differences between sexes were detectable (men: 2.16, women: 2.00, p=0.0055, Effect size: 0.364). Despite substantial sex-related differences in absolute force capacity, relative strength—when adjusted for upper body weight—does not differ meaningfully between men and women. Both sexes are characterized by a physiological strength reserve of approximately 100% of their upper body weight.